From: Wei Liu <wei.liu2@citrix.com>
To: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: Wei Liu <wei.liu2@citrix.com>,
Ian Jackson <Ian.Jackson@eu.citrix.com>,
Jan Beulich <JBeulich@suse.com>,
Xen-devel <xen-devel@lists.xen.org>
Subject: Re: [PATCH] tools/libxc: Fix the reported max_leaf values for PV guests
Date: Wed, 11 Jan 2017 14:32:47 +0000 [thread overview]
Message-ID: <20170111143247.GN1100@citrix.com> (raw)
In-Reply-To: <1484138681-24805-1-git-send-email-andrew.cooper3@citrix.com>
On Wed, Jan 11, 2017 at 12:44:41PM +0000, Andrew Cooper wrote:
> When iterating through CPUID leaves to generating a policy, libxc will clip
> itself at the hardcoded maxima, meaning that no data outside of the hardcoded
> maxima are provided to Xen (in turn, causing Xen to return zeros if these
> leaves are requested.)
>
> The HVM code also clips the max_leaf data reported to the guest, but the PV
> side didn't.
>
> This results in a PV guest using the emulated CPUID, or via Xen using CPUID
> faulting, to observe a max_leaf higher than the toolstack wants, although with
> zeros being returned in the intervening leaves.
>
> Fix the PV side to behave like the HVM side, and clip the max_leaf values in
> leaf 0 and 0x80000000.
>
> Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
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prev parent reply other threads:[~2017-01-11 14:32 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-01-11 12:44 [PATCH] tools/libxc: Fix the reported max_leaf values for PV guests Andrew Cooper
2017-01-11 13:41 ` Jan Beulich
2017-01-11 14:32 ` Wei Liu [this message]
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